Influence of Soft Magnetic Material in a Permanent Magnet Synchronous Machine With a Commercial Induction Machine Stator

This paper presents the efficiency study of a 6-pole and 2-pole induction motor (IM), converted into a 6-pole and 2-pole permanent magnet synchronous machine (PMSM). Firstly, the stator of the IM was kept unchanged and the rotor was converted into a permanent magnet (NdFeB magnets) rotor, resulting in higher average efficiency. Secondly, we investigated how much the efficiency can be increased by replacing the electrical steel in the stator by another material grade. The numerical approach is based on the finite element method (FEM), taking into account the rotor movement. Iron losses are computed according to the loss separation theory. From measurements and simulations, it is observed that the efficiency increases significantly compared to the original IM. The average efficiency of the orig inal 1.5 kW IM converted into the 1.5 kW PMSM led to a 14% higher efficiency in a speed range 0.5Ω_nom - Ω_nom and torque range 0.5T_nom - T_nom. When the stator iron is replaced by M235-35A laminations with the same geometry, the average efficiency increases by an additional 2% for the 1.5 kW PMSM with modified stator.